In any case, you start the mission by going to Sun Camp and heading into the dungeon below it. Argine will contact you first and ask you to betray Grim Onwig; she will give you her chamber key regardless.

Meet Crilgarin next and she will tell you about the Sentry trap. Loot or take the Bag of Winds from the guard in the southern wing, then use it (it is a Consumable) when the game prompts you about it at the threshold to the Sentry.

Once you pass it, save the game and pick the west door to frame Argine, or the east door to frame Grim Onwig.

Get by all the guards and place the book on your chosen target. Escape with your ally afterward. Note that once you complete this mission, items in the Hierophant's dungeon are gone and Sun Camp will be patrolled by hostile gnomes.

All the tasks and trainers will move over to nearby Whitestone (check the buildings for more NPCs), and life goes on.